1. Field of the Invention
The present invention relates to a method for improving the information distribution in a communication network. The present invention is considered to be particularly applicable to any kind of IP networks.
2. Related Background Art
In networks which are based on the Internet Protocol (hereinafter shortly IP), when a host needs to get IP connectivity, it needs first to learn different information regarding the network such as the default router, the prefix information to be used for address auto-configuration, what type of address allocation mechanisms are to be used (stateless or stateful), etc.
As disclosed by T. Narten et al., “Neighbor Discovery for IP Version 6 (IPv6)”, RFC 2461, Internet Engineering Task Force, December 1998, router advertisement messages have been defined in order to carry this necessary information to the hosts. That is, router advertisement messages have been defined in order to carry all the information necessary to the user to get IP connectivity and provide already a quite long set of information.
Currently, several Internet Engineering Task Force (hereinafter shortly IETF) Working Groups are requesting to extend the router advertisement message to carry additional information. For example, the Internet draft by David B. Johnson et Charles Perkins, “Mobility Support in IPv6”, Internet Engineering Task Force, July 2001, proposes to extend the format of the router advertisement message by the addition of a flag bit to indicate that the router sending the advertisement message is serving as a home agent on this link.
Further, the IP Paging mechanisms according to G. Renker et al., “Paging Concept for IP based Networks”, Internet draft, Internet Engineering Task Force, September 2001, need a paging area identity to be broadcasted, and it is currently suggested to extend the router advertisement for this purpose.
Still further, regarding the Hierarchical Mobile IP (HMIP) according to A. Conta et S. Deering, “Internet Control Message Protocol (TCMPv6) for the Internet Protocol Version 6 (IPv6) Specification”, RFC 1885, Internet Engineering Task Force, December 1995, it is also currently suggested to use the router advertisement to provide the information related to the mobile anchorpoint (MAP) entities such as the distance, the preference, the mode, the lifetime, the IP addresses, and other information to the user.
With the Protocol for carrying Authentication for Network Access (PANA), it is proposed to add to router advertisements the identity of the PANA agent which the host should contact to register to the network, or an identity to provide the host with information about the need to register with a different PANA agent.
In conclusion, there is a clear trend according to which router advertisement messages may get very long. Although the length of router advertisement messages may not be a problem in traditional IP networks, when a wireless access link is used (in particular for cellular links) the length of the messages becomes a significant issue. Currently, router advertisement messages are sent in broadcast very frequently; but in case of long messages the frequency would have to be reduced considerably when the access link is wireless to avoid wasting too much bandwidth. Moreover, not every host needs all the information contained in a router advertisement. For example, the IP nodes which only request IP connectivity are not interested in the identity of paging area, MAP information, etc., whereas some users may only be interested in some parts of the information.